Correlation between grain boundaries, carbides and stress corrosion cracking of Alloy 690TT in a high temperature caustic solution with lead

Dai

et al. 2022

MSF

In this paper, the simulated welding structure at different areas of heat affected zone (HAZ) of austenitic stainless steel are prepared by heating furnace, and the deference of intergranular corrosion resistance of all samples were determined by comparative methods of oxalic acid etching, hot-acid test and electrochemical potentiodynamic reactivation tests (EPR), and the effectiveness of all those methods were analysis and determination at the same time. The result shows that the susceptibility degree at different areas of HAZ increased with the heating temperature increase, but all structures can pass hot-acid test and EPR test, indicating that it could maintain good performance of intergranular corrosion resistance. The hot-acid test results have good consistency with EPR test , but inconsistent with oxalic acid etching test. The results show that the evaluation of oxalic acid etching is too much strict to be used as a judgment method, so that not suitable of use for inspection.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Study on Grain Boundary Sensitization in Heat Affected Zone of Austenitic Stainless Steel and its Evaluation Method

Dai

et al. 2022

MSF

“…Moreover, the accumulation of crystal defects at the grain boundaries (GBs) during slip deformation weakens the properties of GBs 23,24 . Under the action of stress, nanoprecipitation occurs at the GBs, which often leads to their reduced cohesion strength 25 .…”

Section: Introductionmentioning

confidence: 99%

Stress-assisted corrosion behaviour of Hastelloy N in FLiNaK molten salt environment

Zhang

et al. 2022

npj Mater Degrad

The use of molten-salt–based energy production and storage systems requires high-temperature corrosion- and creep-resistant structural materials. This study investigated the microstructure evolution and corrosion characteristics of Hastelloy N under working stress in a molten salt environment. Selective diffusion of Cr at the grain boundaries (GBs) of the Hastelloy N degraded the properties of the GBs, making them preferred locations for corrosion crack invasion. Stress further promoted Cr diffusion and accelerated GB carbide precipitation, thereby forming a corrosion couple between the carbide and matrix that facilitated the expansion of intergranular corrosion cracks into the grains. These findings are useful for providing advances in the design of novel structural alloys with extraordinary property-microstructure stability combinations for resistant to complex molten salt environments.

“…Accordingly, the percentage of low-angle grain boundaries (LAGB) was relatively lower in the annealed sample. The HAGB is generally considered to have higher energy than the LAGB [33][34][35] . The KAM maps (Fig.…”

Section: Resultsmentioning

confidence: 99%

Influence of cementite coarsening on the corrosion resistance of high strength low alloy steel

Liu

Che

et al. 2023

npj Mater Degrad

Self Cite

The impact of heat treatment on the initiation and progression of localized corrosion in E690 steel in a simulated marine environment was investigated systematically. The primary cause of localized corrosion was the presence of inclusions, which led to the dissolution of the distorted matrix surrounding them. In the initial stages of corrosion, localized corrosion resulting from inclusions was the predominant form. The chemical and electrochemical mechanisms underlying matrix deformation and localized corrosion caused by inclusions were meticulously elucidated. As the immersion time was extended, the galvanic contributions at the ferrite-austenite interfaces, as well as the coarsened carbides, reduced the polarization resistance in the annealed specimen, accelerating the corrosion rate compared to the lath martensite in the as-received specimen. Consequently, the heat-treated sample promoted a transition from localized to uniform corrosion. Finally, a model was established to describe the corrosion behavior of E690 steel in the marine environment.